PROJECT SUMMARY Cell death has a critical role in wound healing and regeneration following injury, disease or infection. Apoptosis at a site of injury can significantly impact the behavior of surrounding cells, as signals produced by dying cells can induce inflammation, proliferation and dictate the survival of their neighbors. These activities can therefore directly regulate a tissue?s ability to recover from damage. For example, following liver injury in mice, signaling molecules produced by dying hepatocytes drive regenerative proliferation. Thus, a better understanding of how a tissue responds to damage-signals could uncover novel therapeutic interventions to improve wound healing and regeneration. Although advances have been made in understanding how apoptosis contributes to regeneration, little is known about whether non-apoptotic forms of cell death, such as necrosis, might have a similar role. Necrosis occurs in numerous human diseases, particularly following ischemic injury (stroke and heart attack), infections and cancer. Regeneration following necrotic cell death is significantly more variable than that induced by apoptosis, but has been documented in various tissues, suggesting that as yet unidentified and distinct mechanisms might exist in each context. Thus, the aim of this work is to characterize the fundamental genetic mechanisms that lead to regeneration following necrosis versus apoptosis. Evidence that signals from apoptotic cells impact surrounding tissues first originated from studies of the larval wing primordia in Drosophila, an attractive and powerful model to study regeneration. The genetic tools available in Drosophila have led to important insights into the genetic events necessary for regeneration. Studies of regeneration in the larval wing commonly rely on genetic ablation, an efficient and robust approach that permits spatially and temporally controlled cell death to be induced in tissues. However, despite its advantages, this method is also limited in the genetic manipulations that can be achieved, and is lacking the ability to study non- apoptotic forms of tissue loss, such as necrosis. To overcome these problems we have established a new method, DUAL Control, that allows us to induce necrosis or apoptosis in the developing wing primordia, stimulating a regenerative response to either type of damage. Our initial investigations suggest that necrosis and apoptosis lead to dramatically different gene expression changes and morphologies in the surrounding tissue. Importantly, however, regeneration occurs in both situations. As an advance on previous approaches, this novel system also allows us to target genetic manipulations specifically to the surrounding regenerating tissue, independent of ablation. These experiments can therefore take advantage of the large purpose-built RNAi screening libraries available in Drosophila to interrogate regenerating cells directly. We propose to use this new method to characterize the genetic response to damage that leads to successful regeneration following necrosis compared to apoptosis, with a view to identifying novel regulators of regenerative capacity in each context.